We hear Christmas carols and other Christmas music just once a year. Even so I am usually tired of these songs long before Christmas Eve arrives. How many times can one hear, let alone sing, "Hark! The Herald Angels Sing"?
I have found, however, that the old carols remain fresher longer when I focus less on the tunes and more on the lyrics. Many of these carols are actually very well written, full of ideas that a person can find fresh and exciting each Advent season.
"O Little Town of Bethlehem," written by Philips Brooks in 1868, is especially well written. Lines like "The hopes and fears of all the years/Are met in thee tonight" and "Be born in us today" can give any Christian something to meditate about right up until Christmas Eve and beyond.
"Angels, from the Realms of Glory" isn't really a hymn about angels, it turns out. It is a hymn about praise. The first stanza calls on the angels to worship. Subsequent stanzas invite the shepherds, the magi and all of creation, not just human beings, to do the same.
"It Came Upon the Midnight Clear" expresses a similar idea in its last lines, "And the whole world give back the song/Which now the angels sing." In "Joy to the World!" we find, "While fields and floods, rocks, hills, and plains/Repeat the sounding joy." And lines in "Silent Night" read "With the angels let us sing, Alleluia to our King."
Hymns, in general, I believe, are meant to be studied, not just sung on Sunday mornings. If studying them pays no rewards, then singing them seems pointless, however nice the tunes. Pop songs can be full of empty words and get away with it. Not so hymns. They must contains ideas worth thinking about. And ideas, I find, are less likely than tunes to become tiresome.